Fluid transfer systems, such as, for example, hydraulic systems, generally include flexible hoses for transfer of pressurized fluid to components of the fluid system, such as pumps, filters, metal pipes, hydraulic cylinders, and fluid reservoirs. The flexible hoses are often connected with the fluid system components by way of a rigid threaded coupling. Specifically, a first threaded coupling member is attached to one flexible hose, while a second threaded coupling member is bolted, welded, threaded, or otherwise joined rigidly to the fluid system component. The first coupling member is then threadingly engaged with the second coupling member, thus creating a sealed assembly through which fluid may be transmitted.
During the operation of the fluid transfer system, vibration, changing pressures, and changing flow rates can create torsional forces that can loosen the sealed assembly. For example, a large pressure (may be up to 250 or 300 bar in some high pressure systems) or flow rate in a curved portion of the flexible hose can create a force that distorts the trajectory of (e.g., straightens) the flexible hose. Fluctuations in the pressure and other vibrations can create movement and/or torsional forces that can loosen the threaded coupling members. As the couplings begin to separate, the transmitted fluid may begin to leak through the threaded interface between the coupling members. The leaking fluid may lubricate the threads on the first and second coupling members and cause even further loosening. The fluid leakage can result in decreased pressure in the system that diminishes the ability of the system to perform useful work or transmit further fluid. The leakage also wastes fluid, and may create a need for periodic fluid replenishing.
One method of preventing relative rotation of coupling members is disclosed in U.S. Pat. No. 6,557,905 (the '905 patent) issued to Mack et al. on May 6, 2003. The '905 patent discloses a submersible well pump assembly having two connected housings, a clamp ring, and an anti-rotation member. To keep the connection between the two housings secure, the anti-rotation member has cooperative elements associated with each end of the two housings to inhibit rotation of one housing relative to the other. Once placed in compression, the cooperative elements have intermeshing teeth that interlock to inhibit rotation of one adapter relative to the other. The teeth have triangular ridges with radial symmetry that are integrally formed on each end face. The clamp ring is used to put the two housings in compression. The clamp ring is rotatably and slidably carried on the first housing and has internal threads that engage external threads of the second housing to draw the housings together upon threading. Each of the first and second housings connect to the next member in the assembly by a threaded, sealed connection made in a conventional manner.
Although the submersible well pump assembly of the '905 patent may prevent rotation of the first and second housings, it may be incompatible with a flexible hose. Specifically, both of the housings in the '905 patent are joined to the next respective member via a threaded joint. Using a conventional threaded joint to connect each coupling member to the flexible hose may create another location where loosening and separation may occur. In other words, although the ends of the housings that incorporate the anti-rotational member may not loosen relative to each other, the housings may loosen relative to the next respective members. As described above, this loosening may cause leakage and loss of pressure.
The disclosed hose assembly is directed to overcoming one or more of the problems set forth above.